Peat-dewatering process.



UNITED STATES PATENT OFFICE.

THOMAS RIG-BY AND GEORGE W. ANDREW, OIEYDUMFRIES, SCOTLAND, ASSIGNORS TOWETCARBONIZING LIMITED, OF LONDON, ENGLAND.

PEAT-DEWAT'ERING PROCESS.

No Drawing.

To all whom it may concern:

Be it known that we, THOMAS RIGBY and GEORGE IVILLIAM ANDREW, subjectsof the King of Great Britain and Ireland, and residents of 61 Loreburnstreet, Dumfries, Scotland, have invented a certain new and usefulImproved Peat-Dewatering Process, of which the following is aspecification.

This invention relates to the dewatering of peat by a process of theknown kind in which a physical or chemical change is induced in the wetmaterial and the water as a consequence rendered more easilyexpressible.

Ekenberg (see Journal of the Iron and Steel Institute 1909, page 313)showed that if peat was heated while wet to a fairly elevatedtemperature a change of the kind referred to occurred and, apparently asthe result of decomposition of a slimy waterbinding hydrocellulose, thatthe bulk of the water then became readily expressible. This process haslong been accepted as the ideal one for dewatering peat because of thepositive manner of its action and as applicable therefore with certaintyto all the Very different kinds of peats, but despite its advantagesmuch study and expense has been involved in the reduction to the lowestpossible limits of the heat necessary to bring about the change to thefull extent desired. Now we have ascertained that an alternative and insome respects more conveniently available method of securing economy isto utilize theaccelerating power on the reaction which we have foundacids to possess. Thus our experiments show that not only can a greaterdegree of expressibility be secured for any given time of heating at anyparticular temperature, if the peat is acidified but that conversely thesame extent of change can be secured under conditions of lowertemperature or shorter time of treatment or both with acidified peatthan with raw material.

During simple heating of the peat by the Ekenberg method acid mattersare always generated in the peat water and apparently, according to ourinvestigations, the change leading to unbinding of the water does notoccur even in the Ekenberg process until a sufficiency of free acidformed by decomposition consequent on heating is present in the peat. Aparticular advantage Specification of Letters Patent.

Application filed March 6, 1914.

Patented Dec. 15, 1914.

Serial No. 822,972.

of accelerating the reaction by the use of added acid resides however inthe fact that the desired change can then be secured with a lesser lossof nitrogen and solids of calorific value in the effluents the amountsof which bodies dissolved in the peat water when the change is effectedby simple heatlng often becoming serious. According to this inventiontherefore the Ekenberg treatment is carried out after the acidificationof the raw peat. The acid, for instance, hydrochloric sulfuric orsulfurous acid, may be added before the commencement ofthe heattreatment or at some stage during the same. In some cases the acid oracids used may be derived from the effluent separated from a previouslytreated batch of material having been either originally added to that oran earlier previous batch or having been actually formed therein.

The treatment may most conveniently be carried out according to eitherof the Ways indicated in application N 0. 712745 differing chiefly onlyin the temperature and time of treatment of the material in the hottestportion of the wet-carbonizing apparatus the material being afterwarddewatered by pressing preferably still at a fairly elevated temperaturesay above 60 C. in the usual way.

As an instance of the effect produced by some acids we may state that incertain of our experiments on a particular peat which when using simpleheating needed to be maintained at 180 C. for some twenty minutes tosecure a certain ease of removal of the water, this peat after it hadhad an amount of acid (hydrochloric, sulfuric or sulfurous acid) addedto it sufficient to render the acidity'of the pulp to 7 %that of anormal solution of the acid was capable of being just as easilydewatered after heating it for a few minutes to a temperature even below100 C. In fact in some experiments with sulfurous acid satisfactoryresults were obtained even after only heating the material for fiveminutes to a tempera ture of 60 C.

Having now described our invention, what we claim as new and desire tosecure by Letters Patent is 1. A process for dewatering peat consistingin acidifyingthe wet peat, heating same 7 while wet and withoutevaporation only until the material loses its water-binding propertiesand then expressing the liberated water, as set forth.

7 2. Aprocess for dewatering peat consist-,

1 that of one-tenth to one twentieth normal solution of the acid,heating the acidified pulp without evaporation for a time suffi- Copiesot thispatent may 'nev obtained for cient only to liberate the boundwater and pressing the liberated water out of said peat; as set forth.

4:. A process for dewatering peat consisting in heating peat while wetand without evaporation for a time sufficient to unbind the water of themass, removing the lib- .erated water from the peat mass, and addingacid matters contained 111 said liberated water to a further quantity ofpeat about to undergo treatment; as set forth.

In testimony whereof we have signed our names to this specification inthe presence of two subscribing witnesses.

' T. RIGBY.

G. W. ANDREW.

Witnesses:

BERTRAM H. MATTHEWS, C. S. DEALTRY.

five cents each, by addressingthe Gommissioner of Patents, Washington,D. 0. s

